This application pertains to the art of engineered lighting systems, and more particularly to engineered lighting systems for lighting of specimens in an inspection environment.
The invention is particularly applicable to video inspection apparatuses and will be described with particular reference thereto, although it will be appreciated that the invention has broader applications such as lighting of specimens in any inspection or computer vision system.
Machine vision systems are obtaining increasing significance in industry to aid in robotic assembly systems as well as inspection systems for quality control. Such machine vision systems are generally comprised of a lighting system to light a specimen and a camera for sensing light reflected therefrom. A digitized image is formed from an image received by the camera. The data of this image is then available for use in controlling a robot arm, indentifying the specimen, or determining whether the specimen is acceptable to specified standards. The ability to govern operations in accordance with an inspected specimen is dictated by the quality of the digitized image.
Early attempts on improving the accuracy of image data were directed to improvements in cameras and performance of algorithms on captured image data, in an effort to improve integrity, contrast, or resolution thereof. Little emphasis was placed on the lighting systems, which, in a typical video inspection system, were comprised of inert gas strobe lamps, such as xenon strobes, particularly when specimens are in motion relative to the video camera. For non-moving specimens, common steady-state light sources such as fluorescent, quartz-halogen, incandescent, or the like, are typically used.
Such video lighting systems are plagued by a variety of problems. Placement of a single lamp over a specimen which includes a reflective surface often causes an image of the strobe lamp itself to be transmitted to an inspection device. Strobe lamps were also relatively expensive, varied in intensity from flash to flash, and tended to degrade over a period of time, thereby resulting in lessened resolution of a resultant video image. In applications in which many hundreds or thousands of inspections per minute are required, in addition to poor lighting characteristics, the strobes also require regular replacement, which resulted in additional down time of the entire inspection apparatus.
The present invention contemplates a new and improved apparatus and method for lighting of a specimen in a video inspection environment which overcomes all the above-referred problems and others, and provides a video inspection lighting system with increased resolution and longetivity.